Computers are often connected together as part of a Local Area Network (LAN). The LAN permits computers to share data and programs with one another. Many typical LANs are based upon physical connections between individual computers and a server, for example. The connections may be twisted pair conductors, coaxial cables, or optical fibers, for example.
There is also another class of LAN based upon wireless communication to the individual computers. A wireless LAN is not restricted to having physical connections to the individual computers. Accordingly, original installation may be simplified. Additionally, one or more of the computers may be used in a mobile fashion. In other words, the user may use a laptop computer and move from place to place while still being connected via the wireless LAN.
In particular, the IEEE standard 802.11 is directed to a wireless LAN. The IEEE 802.11 standard defines the protocol for several types of networks including ad-hoc and client/server networks. An ad-hoc network is a simple network where communications are established between multiple stations in a given coverage area without the use of an access point or server. The standard provides methods for arbitrating requests to use the medium to ensure that throughput is maximized for all of the users in the base service set.
The client/server network uses an access point that controls the allocation of transmit time for all stations and allows mobile stations to roam from one access point to another. The access point is used to handle traffic from the mobile radio to the wired or wireless backbone of the client/server network. This arrangement allows for point coordination of all of the stations in the basic service area and ensures proper handling of the data traffic. The access point routes data between the stations and other wired/wireless stations or to and from the network server.
Of course, two or more LANs may be interconnected using wireless LAN devices at respective access points. This may be considered a network bridge application.
Security is addressed in the 802.11 standard as an option and may be accomplished by an encryption technique known as the Wired Equivalent Privacy (WEP) algorithm. This algorithm is based on protecting the transmitted data over the radio transmission using a 64-bit seed key and the RC4 encryption algorithm. WEP, however, only protects the data packet information and does not protect the physical layer header. This is so that other stations on the network can listen to the control data needed to manage the network. Unfortunately, this may provide a reduced level of security.
To provide higher levels of security, more powerful cryptographic equipment is available, such as a TACLANE KG-175. This equipment provides confidentiality and end-to-end authentication to protect sensitive information. Unfortunately, for a wireless LAN, such a device is relatively bulky and expensive.